This invention relates to plate tumblers for cylinder lock mechanisms. More particularly, the invention relates to an improved plate tumbler and to a cylinder lock mechanism incorporating the tumbler.
Plate tumbler-type cylinder lock mechanisms are susceptible to picking by an operation which involves applying to a plug assembly in the lock mechanism a torque tending to rotate the plug assembly relative to a surrounding barrel, in the direction of an unlocking position of the plug assembly, while operating on tumblers in the plug assembly with a picking tool to place them in release positions. The tumblers project from the plug of the assembly into interlocking engagement with the barrel, and the tool, which may embody a wire or the like, is inserted in a keyway in the plug and into engagement with the tumblers. The tumblers are acted upon by the tool so as to withdraw them from the interlocking engagement and lodge them within the barrel, against an inner surface thereof, as the plug turns slightly under the torque force. Picking of the lock is complete when all of the tumblers are lodged within the barrel, and the plug assembly then is free to rotate to its unlocking position.